The Seattle Seahawks have already announced the firings of their top four assistant coaches, including their two coordinators, plus a mutual parting of ways with a fifth. A few others are not expected to return as a result of the biggest overhaul of Pete Carroll's staff since he took over as head coach in 2010.

A similarly drastic retooling of the roster could follow in the wake of a 9-7 finish that snapped Seattle's string of five straight playoff appearances. That's the belief among some observers and at least a few of the players themselves.

In response to Bennett on the possibility of a significant roster shake-up, tight end Luke Willson told the same station, "I would agree. Hopefully I'm not part of that turnover. I guess we'll find out soon."

Willson is one of 16 Seahawks scheduled to become unrestricted free agents. That group also includes tight end Jimmy Graham, defensive tackle Sheldon Richardson and wide receiver Paul Richardson, among other starters. We'll examine their situations in the coming weeks as free agency draws nearer.

Here is a look at three other longtime Seahawks who are under contract but may not be back in 2018 for reasons including age, health, salary and/or other contractual dynamics. Like Chancellor and Avril, they've been key members of a Seahawks defense that allowed the fewest points in the NFL from 2012 to 2015 but slipped to third and then a tie for 13th over the past two seasons.

FS Earl Thomas

Age: Turns 29 in May

Contract status: Entering the final year of a four-year, $40 million extension

Recent comments from Thomas to ESPN set the stage for a potential holdout in the absence of a multiyear extension at his desired price. We can safely assume that price at least matches, if not tops, the $13 million average of Eric Berry's latest deal with the Kansas City Chiefs, which he signed last offseason to become the NFL's highest-paid safety. Thomas, coming off his sixth Pro Bowl appearance and arguably the most important player to Seattle's defense, would be well within reason to ask for that type of compensation. The Seahawks would be well within reason to balk given the inherent risk of making that large of a financial commitment to a player who is approaching 30 and has missed seven games over the past two seasons because of three injuries. An impasse could lead the Seahawks to shop Thomas in trade talks like they did under much different circumstances with Sherman last offseason. Thomas is a once-in-a-generation player, but if he digs his heels in and if another team makes Seattle a worthwhile offer, pulling the trigger on a trade wouldn't be out of the question even if it wouldn't make the Seahawks better right away.

CB Richard Sherman

Age: Turns 30 in March

Contract status: Entering the final year of a four-year, $56 million extension

Sherman, like Thomas, is one of the most iconic players in franchise history. He was again playing at an All-Pro level when his season ended in November because of a ruptured Achilles. He has a good chance at being ready by the start of next season based on the typical recovery period for that injury. It should be noted that he appeared to hit the reset button during an incident-free season after a tumultuous 2016 that included a pair of sideline blowups toward coaches. All of that could work in favor of Seattle bringing Sherman back in 2018, especially because his injury figures to severely diminish his trade value. On the other hand, there are no guarantees with injuries as significant as Sherman's. He also carries a 2018 salary-cap charge of $13.2 million with only $2.2 million in dead money, meaning the Seahawks could save a whopping $11 million if they were to cut him. They could wait to make any decision on Sherman until after free agency and the draft, which would allow them to assess their cornerback situation and Sherman's health first.

DL Michael Bennett

Age: Turns 33 in November

Contract status: Signed through 2020 on a three-year, $30.5 million extension

It was only 14 months ago that Seattle gave Bennett a new contract that came with a raise he had been seeking since 2015, but the possibility of the Seahawks releasing him seems real despite that. He even acknowledged as much at season's end, telling The News Tribune that he "probably won't be back next year." It's not as though Bennett's 2017 season was a disappointment. Yes, he continued to struggle with penalties, as did the Seahawks as a team. But Bennett remained a disruptive force when he wasn't jumping offside. He finished second on the team with 8.5 sacks and again led Seattle's defensive linemen in snaps -- by a wide margin -- despite playing with foot and knee injuries.

The Seahawks would incur a little over $5.2 million in dead-money charges by releasing Bennett because it's so early in his extension. The cap savings would be just under $2.2 million, which is not much. That coupled with the strong possibility that Avril won't be able to play again -- or is released before that determination is made -- could lead the Seahawks to give Bennett another season. It's also conceivable that they bite the salary-cap bullet and move on from Bennett now with an eye toward avoiding the possibility of his age and further injury leading to a rapid decline in his effectiveness. If the Seahawks do release Bennett, expect it to happen before he's owed a $3 million roster bonus in March.